Drop background color optimization for composited layers

Source/core/rendering/CompositedLayerMapping.h

Index: Source/core/rendering/CompositedLayerMapping.h
diff --git a/Source/core/rendering/CompositedLayerMapping.h b/Source/core/rendering/CompositedLayerMapping.h
index a1f39e83617e454fe1a6e829a65207fad0b5135a..b7407cdbaa1debd10942e9b72ad3b1a3359e77ce 100644
--- a/Source/core/rendering/CompositedLayerMapping.h
+++ b/Source/core/rendering/CompositedLayerMapping.h
@@ -233,7 +233,7 @@ private:
     void updateScrollParent(RenderLayer*);
     void updateClipParent(RenderLayer*);
     bool updateSquashingLayers(bool needsSquashingLayers);
-    void updateDrawsContent(bool isSimpleContainer);
+    void updateDrawsContent();
     void updateChildrenTransform();
     void registerScrollingLayers();
 
@@ -260,20 +260,18 @@ private:
 
     bool isMainFrameRenderViewLayer() const;
 
-    bool paintsBoxDecorations() const;
     bool paintsChildren() const;
 
-    // Returns true if this compositing layer has no visible content.
-    bool isSimpleContainerCompositingLayer() const;
     // Returns true if this layer has content that needs to be rendered by painting into the backing store.
-    bool containsPaintedContent(bool isSimpleContainer) const;
+    bool containsPaintedContent() const;
+    bool paintsIntoOwningLayer() const;

[alokp, 2014/02/26 22:11:16]

I do not understand what this function is returning. Who paints into owning
layer? Please add a comment.

     // Returns true if the RenderLayer just contains an image that we can composite directly.
     bool isDirectlyCompositedImage() const;
     void updateImageContents();
 
     Color rendererBackgroundColor() const;
-    void updateBackgroundColor(bool isSimpleContainer);
-    void updateContentsRect(bool isSimpleContainer);
+    void updateBackgroundColor();
+    void updateContentsRect();
 
     void updateCompositingReasons();